1. Field of the Invention
The present invention relates to a twist vibrator utilizing a piezoelectric bimorph.
2. Brief Description of the Prior Art
Japanese Patent Publication No. Hei 5-13401 provides a piezoelectric bimorph, i.e. a twist vibrator, having twisted opposite ends, which comprises a pair of piezoelectric ceramic members having a rectangular shape and cemented to each other, each of the piezoelectric ceramic members being divided into four quadrants, whereby the piezoelectric ceramic members are bent in one direction of thickness at one diagonal corner thereof and in the other direction of thickness at the other diagonal corner thereof, thus permitting the pair of piezoelectric ceramic members, or piezoelectric bimorph as a whole, to perform twist vibratory motion.
However, the above conventional device has the following shortcomings and/or inconveniences.
That is, with such twist vibrator, although only one end is used as an output end for performing twist vibratory motion, the other end is also wastefully designed to perform twist vibratory motion. Since the twist vibrator is of a construction vibrating at opposite ends thereof, excessive ceramic material is used and therefore economic efficiency is inferior. Furthermore, the piezoelectric bimorph becomes large in size.
Also, since the twist vibrator performs twist vibratory motion at opposite ends thereof, its fixing area with respect to a support member is limited. For example, if its opposite end with respect to the output end is fixed, since the twist vibratory motion, which would otherwise be performed as initially intended, of such opposite end is restrained or stopped due to fixing thereof, the reaction causes the amount of twist vibratory motion of the output end to be reduced.
Although the center (node of vibration) of twist vibration of the piezoelectric bimorph can be used as a fixing area, the position of such node is very difficult to specify. In addition, since an area required for fixture is difficult to obtain, firm fixing to a support member is also very difficult.